The present invention relates to surface planers. More specifically, the present invention is concerned with presser rolls for centering and feeding lumber to a surface planer.
Surface planers are commonly known for surfacing workpieces. Such machines are provided with one or more heads that include, for example, an abrasive belt or a plurality of teeth. It is to be noted that the expression xe2x80x9csurfacingxe2x80x9d is intended hereinbelow to include any surfacing operation, such as sanding and grinding.
Many surface planers are provided with two opposite abrasive heads, thus allowing simultaneous processing of both sides of a workpiece, A precise spacing of the two opposite heads allows the operator to control of the thickness of the resulting workpiece. Although such control may be accurate for straight lumber, problems arise with lumber that is significantly warped. Indeed, the warpage may cause unequal surfacing on both sides of the lumber.
According to the prior-art, opposite and fixedly mounted rollers are generally provided upstream of the abrasive heads as a feed system forcing the warped lumber therethrough.
A drawback of fixedly mounted rollers is that they may cause badly warped lumber to crack under the pressure generated by the two rollers.
Another drawback of feeding systems equipped with fixed rollers is that they limit the precision of the planing process. Indeed, lumber having a thickness less then the nominal value may be surfaced unequally on both sides and a thicker piece may be too large for the feeding system.
A solution to these drawbacks has been proposed by Gerber in U.S. Pat. No. 4,322,919, issued on Apr. 6, 1982 and entitled xe2x80x9cSelf-Centering Feed Mechanism for an Abrasive Grinding Machinexe2x80x9d. Gerber proposes a feeding system that includes a control arm mechanism provided with pneumatic actuator that permits the control arm mechanism to be deflected away from the center plane as it engages a workpiece.
A first drawback of Gerber""s system is that it cannot be installed in a conventional planer without making modifications thereto. Moreover, Gerber""s system has several mechanical components, therefore increasing the need for maintenance and the possibility of malfunctions.
Gerber""s system is also relatively bulky and takes up working space.
More specifically, in accordance with the present invention, there is provided a presser roll for a surface planer comprising:
a longitudinal shaft;
a generally cylindrical sleeve mounted on the longitudinal shaft for rotation in unison therewith; the sleeve being radially deformable; and
a biasing assembly mounted between the shaft and the sleeve; the biasing assembly outwardly biasing the sleeve.
Other objects, advantages and features of the present invention will become more apparent upon reading the following non-restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.